kmart888

Most folks here seem more interested in the quality of the exhaust sound than the actual performance gained when discussing exhaust systems. I am more interested in performance first followed closely by quiet and stealth, therefore I am considering replacing my MXP II muffler with the stock oem muffler, nothing wrong with the MXP, it is quiet and sounds good but I would just prefer a stock noise level. I am thinking (hoping) that there will be little if any performance hit in changing back to the oem muffler.

My present mods are in my signature, I'm adding a BBX turbo and AMS "widemouth" DP next week.

Rather than going to the trouble of doing a before and after dyno tune I'm looking for opinions (performance not my sanity) first, if it looks like I may take a noticeable performance hit by changing the muffler back to oem I shall not this "downgrade"

Gqracer

iTrader: (1)

Yeah, Im in the same boat too. Is it worth paying $600 ^ for an additional .5 inch diameter size exhaust? My preference is to keep the stock noise level and stealth. But then again, if it is +10 ^ whp possible gain, Im ***** to sacrifice to avoid damn Cali cops.

FedEvo8

http://www.worksevo.com/store/produc...roducts_id=502

Probably what would work best in your situation...

kmart888

Not sure, they don't say what they modify. I heard they mostly just remove the internal flapper valve, if that is the case the modified oem muffler would increase noise at part throttle whilst doing little at wot; not what I want.

They (works) claim +12 hp but offer no cooberating (sp?) evidence.

Chang_Wufei_05

iTrader: (3)

http://www.roadraceengineering.com/evox/rreexhaust.htm incl. an option to gut stock muffler

kmart888

Not interested, this process would most likely give me a stock appearing muffler that is noisy at part throttle and as restrictive as oem at wot. It (the gutted oem muffler) is not as well engineered as the aftermarket muffler solutions (I already have a good one in the MXP II). What I want is stock noise level, forget being totally stealth for the time being I am most likely going to paint the OEM muffler black if I decide to go this route anyway.

I am trying to ascertain how restrictive the OEM muffler really is. not very is my gut feeling. In this thread and the similar one I started in the other forum a few knowledgeable folks expressed the opinion the OEM muffler will result in a big HP loss (2.5” inlet, and “common sense”) but their arguments are not convincing. I have decided I shall attempt a before and after dynotune on my car next month when Cobb So Cal opens and I can schedule an appointment. At least one other X owner has expressed interest in my findings, if I take more than a 10 hp hit I will revert back to the aftermarket muffler.

stay tuned

kmart888

My car has been down for the last 3 months so I may have forgotten what it sounded like back in September but I just drove it from San Francisco to Los Angeles with the new BBX full turbo and AMX 'Widemouth' DP running on 91 octane (I normally ran the old setup on E85) and I think it is even quieter than before, weird eh?

I will probably still do the before and after dyno run on the OEM muffler just to prove a point but there is now less incentive to do so.

MIVEC 4G63

iTrader: (13)

i am trying the same thing now, just broke 1000 miles, gonna do an oil change and then high flow cat intake and a tune, gonna see how we do.

edogg23

iTrader: (2)

If you trulely care about performance first Then I wouldn't put the stock muffler on. Necking down would make the rest of your 3" exhaust kind of pointless.

kmart888

I do care, truly!

What you say has been repeated ad-nausium (except for Bryan who almost supported my view point) but no flow bench or dyno evidence of this assertion has been presented. It is my gut feeling that noise vs flow is more a function of how large and well designed the muffler is than just the 3" vs 2.5" inlet and by me reverting to the stock muffler I will lose less then 5hp and gain the almost stock noise level with the resonated test pipe I strive for. Only an objective before and after dyno run will settle the argument.

ODUB

iTrader: (8)

you might not lose much in performance by going back to the stocker, but you did waste money on a downpipe.

edogg23

iTrader: (2)

Well I know this is really apple to oranges but i do remember seeing a thread where someone did a dyno on an VIII or IX with a silencer on their after market exhaust and it lost like 30 hp. The sliencer is probably a lot worse than a stock muffler but the point is that necking down at the end of the exhaust *should* cause a noticable reduction in power.

kmart888

Why would you say that? I feel that there are a number of dyno runs, though I cannot find one at the moment, that show the AMS dp works rather well in conjunction with the Red/BBX size turbo, perhaps a waste if I was still running a stocker.

kmart888

"*should*", seems no one has actually tested because they are more interested in how it *sounds* and assumes noise = performance, unlike me they want their car to sound racy. An actual test is the only way to be sure, I hope I can do a test in the near future, perhaps January.

Don't get me wrong, I am not opposed to a melodious engine sounds per se, I love the sound of my V8 Miata (5.0 Ford) with dual 3" Borla mufflers, and that of my S2000 at 9000 rpm's with the HKS Legamax, and my old SRT4 (sold) with a custom 3" side exit, I'm just not terribly enamored with the sound of the Mitsubishi!

The custom exhaust on the Ford V8 and the SRT4 made a noticeable seat of the pants increase in performance, the HKS on the Honda did zilch (I attribute this to Honda having done a pretty good job of designing the oem mufflers in the first place) If I find I can run the stock muffler on the Evo without a noticeable decrease in performance I should do so, otherwise I will admit defeat and give up on this whole misbegotten endevour.

Merry Christmas everyone!

Paul

Crackerballer

iTrader: (1)

^^I'm with you. The internet has created a new kind of car owner, where we can get online and listen to 1,000 sound clips but have to search for hours to find a single dyno chart. I wish more people would baseline their cars and then dyno after every mod, it would be such a great addition to the plethora of information already on this site.